Techniques for power saving operations in a wireless network

ABSTRACT

Various embodiments are generally directed to an apparatus, method and other techniques to initiate a transaction session at a transaction session start time to communicate a transaction between a first device and a second device, receive a first frame comprising information indicating an occurrence of another transaction session between other devices and a time reservation to reserve time for the other transaction session, receive a second frame comprising second information indicating a truncation of the other transaction session at a truncation time and before an expiration of the time reservation, and shift a subsequent transaction session start time for at least one subsequent transaction session between the first device and the second device based on a difference between the transaction session start time and the truncation time.

TECHNICAL FIELD

Embodiments described herein generally relate to techniques to avoidinterference while communicating a wireless network.

BACKGROUND

Technological developments permit digitization and compression of largeamounts of voice, video, imaging, and data information. The need totransfer data between devices in wireless communication requirestransmission of a data transactions in diverse and dynamic environmentsat a high data rate. Wireless Personal Area Networks (WPAN)communication systems are extensively used for high data exchangebetween devices over short distances. Current WPAN systems exploit thefrequency band in the 2-7 GHz frequency band region and achieve veryhigh throughputs.

The availability of 7 GHz of unlicensed spectrum in the 60 GHz band andthe progress in the semiconductor technologies are pushing thedevelopment of the mm Wave WPAN and mm Wave Wireless Local Area Network(WLAN) systems which will operate in the 60 GHz band and will achievethe throughputs of about several Gbps. Multi-gigabit speeds may enablehigh performance wireless data, display and audio applications thatsupplement capabilities of current wireless local area network (LAN)devices.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates an exemplary embodiment of a communication system.

FIG. 1B illustrates an exemplary embodiment of a second communicationsystem.

FIG. 2 illustrates an exemplary embodiment of a timing diagram.

FIG. 3A illustrates an exemplary embodiment of a second timing diagram.

FIG. 3B illustrates an exemplary embodiment of a third timing diagram.

FIG. 4 illustrates an exemplary embodiment of a first logic flowdiagram.

FIG. 5 illustrates an exemplary embodiment of a fourth timing diagram.

FIG. 6 illustrates an exemplary embodiment of a Grant frame.

FIG. 7 illustrates an exemplary embodiment of a CF-End frame.

FIG. 8A illustrates an exemplary embodiment of a second logic flowdiagram.

FIG. 8B illustrates an exemplary embodiment of a third logic flowdiagram.

FIG. 9 illustrates an exemplary embodiment of a fourth logic flowdiagram.

FIG. 10 illustrates an exemplary embodiment of a computing architecture.

DETAILED DESCRIPTION

Various embodiments are generally directed to an apparatus, system andmethod for energy efficient wireless communications. Some embodimentsmay be directed to operations according to one or more standards, suchas those defined by the Wireless Gigabit Alliance Wireless Gigabit(“WiGig”) Specification Version 1.0, according to Institute ofElectrical and Electronics Engineers (IEEE) Draft StandardP802.11ad®/D9.0, published July 2012, titled “Amendment 3: Enhancementsfor Very High Throughput in the 60 GHz Band,” (“IEEE 802.11ad Revision9.0”), and/or according to any predecessors, revisions, or variantsthereof (collectively, “the WiGig/802.11ad Standards”). It is to beunderstood that embodiments are also possible and contemplated that donot include a WiGig/802.11ad wireless network, and that the embodimentsare not limited in this context.

Some embodiments may be directed to communicating a transaction during atransaction session between two or more wireless devices or stations.When communicating a transaction the stations may send and receive anumber of frames to communicate information and data. Further, whencommunicating the transactions the stations may operate in apeer-to-peer private basic service set (PBSS) over one or more channelsin a frequency spectrum that may be shared with other devices and/orstations. Thus, various embodiments may be directed to takinginterference avoidance actions to avoid interference while communicatingover the one or more channels and conserving power by efficientlyscheduling and adjusting the communications of the transactions.

More specifically and in some exemplary embodiments, one or morestations in a PBSS may detect interference caused by other devicescommunicating a transaction. The detecting station may wait for theother devices to complete the transaction before it commencescommunication of its own transaction during a transaction session. Thedetecting station may also determine a difference between the completionof the communication of the transaction between the other devices andthe start of its own transaction session. The difference may be used toadjust or shift subsequent transaction session start times forsubsequent transaction sessions. By shifting a subsequent transactionsession start time, the stations may realize significant power savingsbecause they may remain in a standby mode of operation for a longerperiod of time. Further embodiments may be directed to communicatingtransaction session start times by utilizing a combination of frames,such as communicating a Grant frame followed by a contention-free end(CF-End) frame. These and other details will become more apparent in thefollowing description.

Various embodiments also relate to an apparatus or systems forperforming these operations. This apparatus may be specially constructedfor the required purpose or it may include a general-purpose computer asselectively activated or reconfigured by a computer program stored inthe computer. The procedures presented herein are not inherently relatedto a particular computer or other apparatus. Various general-purposemachines may be used with programs written in accordance with theteachings herein, or it may prove convenient to construct morespecialized apparatus to perform the required method. The requiredstructure for a variety of these machines will appear from thedescription given.

Reference is now made to the drawings, wherein like reference numeralsare used to refer to like elements throughout. In the followingdescription, for purposes of explanation, numerous specific details areset forth in order to provide a thorough understanding thereof. It maybe evident, however, that the novel embodiments can be practiced withoutthese specific details. In other instances, well-known structures anddevices are shown in block diagram form in order to facilitate adescription thereof. The intention is to cover all modifications,equivalents, and alternatives consistent with the claimed subjectmatter.

FIG. 1A illustrates an exemplary embodiment a communications system 100.In various embodiments, the communications system 100 may includemultiple wireless nodes 104-n communicating 108-n in a wireless network102. A wireless node generally may include any physical or logicalentity for communicating information in the communications system 100and may be implemented as hardware only, software only, or anycombination thereof, as desired for a given set of design parameters orperformance constraints. Although FIG. 1A may show a limited number ofnodes by way of example, it can be appreciated that more or less nodesmay be employed for a given implementation.

The wireless network 102 may communicate information in accordance withone or more standards as promulgated by a standards organization. Insome embodiments, for example, the wireless network 102 may include a 60GHz multi-gigabit wireless network. For example, in various embodiments,communications system 100 may be implemented according to WirelessGigabit Alliance Wireless Gigabit (“WiGig”) Specification Version 1.0,according to Institute of Electrical and Electronics Engineers (IEEE)Draft Standard IEEE Std 802.11ad™-2012. It is to be understood thatembodiments are also possible and contemplated that do not include aWiGig/802.11ad wireless network, and that the embodiments are notlimited in this context.

The wireless network 102 may communicate, manage, or process informationin accordance with one or more protocols. A protocol may include a setof predefined rules or instructions for managing communication amongnodes. In various embodiments, for example, the wireless network 102 mayemploy one or more protocols such as a beam forming protocol, mediumaccess control (MAC) protocol, Physical Layer Convergence Protocol(PLCP), Simple Network Management Protocol (SNMP), Asynchronous TransferMode (ATM) protocol, Frame Relay protocol, Systems Network Architecture(SNA) protocol, Transport Control Protocol (TCP), Internet Protocol(IP), TCP/IP, X.25, Hypertext Transfer Protocol (HTTP), User DatagramProtocol (UDP), a contention-based period (CBP) protocol, a distributedcontention-based period (CBP) protocol and so forth. In variousembodiments, the communications system 100 also may be arranged tooperate in accordance with standards and/or protocols for mediaprocessing. The embodiments are not limited in this context.

As shown in FIG. 1A, the communications system 100 may include a network102 and a plurality of wireless nodes 104-n, where n may represent anypositive integer value. In various embodiments, the wireless nodes 104-nmay be implemented as various types of wireless devices and stations. Insome embodiments, wireless nodes 104-n may include mobile and/or fixedwireless devices capable of communicating according to a wirelesscommunications protocol of communication system 100. In addition and insome embodiments, wireless nodes 104-n may include directionalmulti-gigabit (DMG) stations (STAs) operative to communicate overwireless network 102 according to the WiGig/802.11ad Standards.

In various embodiments, communications of wireless nodes 104-n overwireless network 102 may be managed and/or configured by a wireless node104-n operating as a control node, which may be any one of the wirelessnodes 104-n or a separate device (not shown), such as an access point ora base station. In some embodiments, a control node may include apersonal basic service set (PBSS) control point (PCP) and/or an accesspoint (AP) according to the WiGig/802.11ad Standards. In variousembodiments, a control node may be operative to determine one or morecommunications parameters governing communication by one or morewireless nodes 104-n over wireless network 102. It is worthy of notethat in some embodiments, a control node may itself include acommunications device, and may operative to determine one or morecommunications parameters governing its own communication over wirelessnetwork 102. For example, in various embodiments, a control node mayinclude an 802.11ad PCP, and thus may itself constitute an 802.11ad STA,and may determine one or more communications parameters governingcommunication between itself and other wireless nodes 104-n overwireless network 102. The embodiments are not limited in this regard.

In some embodiments, the wireless nodes 104-n may include one morewireless interfaces and/or components for wireless communication such asone or more transmitters, receivers, transceivers, chipsets, amplifiers,filters, control logic, network interface cards (NICs), antennas,antenna arrays, modules and so forth. Examples of an antenna mayinclude, without limitation, an internal antenna, an omni-directionalantenna, a monopole antenna, a dipole antenna, an end fed antenna, acircularly polarized antenna, a micro-strip antenna, a diversityantenna, a dual antenna, an antenna array, and so forth.

In various embodiments, the wireless nodes 104-n may include or formpart of a wireless network 102 which may allow for peer-to-peer or adhoc network communications. The wireless nodes 104-n may communicatedirectly with each other without necessarily needing a fixed device,such as a wireless access point. In some embodiment, for example, thewireless network 102 provides for contention-based medium access, suchas carrier sense multiple access (CSMA) technique, often combined with acollision avoidance (CA) technique for wireless networks (CSMA/CA). TheCSMA/CA technique is intended to provide fair and equal access to thewireless nodes 104-n, where each wireless node 104-n listens to thewireless shared medium before attempting to communicate.

However, when the wireless nodes 104-n are listening and waiting tocommunicate or the wireless shared medium, significant amounts of powermay be consumed. Thus various embodiments may be directed to thewireless nodes 104-n employing various power saving techniques todynamically schedule and align transactions of multiple interferingdevices. More specifically and as will be discussed in more detailbelow, various embodiments may include dynamically changing an allocatedperiod of time for a transaction sessions including shifting the starttimes for transaction sessions based on observed link occupancy. Thus bydynamically shifting transaction session start times and transactionperiods based on link occupancy, the wireless nodes 104-n may moreoptimally enter and exit a power saving mode putting circuitry into asleep or low power state between one or more intervals to communicatetransaction between the wireless nodes 104-n.

FIG. 1B illustrates a second exemplary embodiment of a communicationssystem 150. In various embodiments, communications system 150 may besimilar to and operate in a similar manner as communications system 100previously discussed above. For example, communications network 150 mayoperate according to the WiGig/802.11ad Standards.

According to some exemplary embodiments, communications network 150, mayinclude stations 160, 170, 180 and 190. Stations 160, 170, 180 and 190are depicted as stations (STA) e.g., STA A, STA B, STA C, and STA D,respectively. In various embodiments stations 160, 170, 170 and 190 maybe similar to or the same was any one of the wireless nodes 104-ndiscussed above with respect to FIG. 1A. Various embodiments are notlimited in this manner.

Furthermore, according to some exemplary embodiments, a pair ofstations, for example STA A 160 and STA B 170, and STA C 180 and STA D190, may share a direct link of a privet basic service set (PBSS). Forexample, STA A 160 and STA B 170 may make up a first PBSS and mayestablish a direct link 142, and STA C 180 and STA D 190 may make up asecond PBSS and may establish a direct link 144. It should be understoodthat the first and second PBSS may be neighboring networks which may notbe able to transmit during a protected time or reserved time forcommunication established by one of the networks or stations within oneof the PBSSs. In addition, the direct links 142 and 144 may share thesame channel for communication, if desired.

As illustrated in FIG. 1B, STA A 160 may include a processor component162, a memory component 164, a beamformer 166 and a transceiver 168.Further, the STA A 160 may include one or more antennas 167 coupled withthe beamformer 166 and transceiver 168. The antennas may be comprised ofone or more antenna elements to build phased array. The phased array maybe set by the beamformer 166 in accordance with a beamforming protocol.The one or more antennas 167 may provide multiple-input-multiple-output(MIMO). However, various embodiments are not limited in this manner.

In various embodiments, processor component 162 may be any processor andmay be capable of executing instructions to operate and/or controlwireless communication devices according to embodiments (e.g., 60 GHzWPAN medium access controller (MAC)). The processor component 162 may beone or more of any type of computational element, such as but notlimited to, a microprocessor, a processor, central processing unit,digital signal processing unit, dual core processor, mobile deviceprocessor, desktop processor, single core processor, a system-on-chip(SoC) device, complex instruction set computing (CISC) microprocessor, areduced instruction set (RISC) microprocessor, a very long instructionword (VLIW) microprocessor, or any other type of processor or processingcircuit on a single chip or integrated circuit. For example, theprocessor component 162 may include a graphical processing unit (GPU)for processing graphical and video information, in various embodiments.Although FIG. 1B only illustrates one processor component 162 variousembodiments are not limited in this manner and the STA A 160 may includeany number of processor components having any number of cores. Theprocessor component 162 may be connected to and communicate with theother elements of the computing system via an interconnect, such as oneor more buses, control lines, and data lines.

Memory component 164 may include one or more of random access memory(RAM), read-only memory (ROM), electrically erasable programmableread-only memory (EEPROM), flash memory, and hard disk memory. Thememory component 162 is not limited to these memory components. Forexample, the memory component 162 may include a non-transitorycomputer-readable storage medium. These memory components can store datamomentarily, temporarily, or permanently. The memory component 164stores instructions and data for STA A 160. The memory component 164 mayalso store temporary variables or other intermediate information whilethe processor component 162 is executing instructions. In someembodiments, the memory component 164 is configured to store varioustypes of data, including, without limitation, information and contentfor operating in an 802.11ad network.

Transceiver 168 may include a plurality of transmitters (TX) and aplurality of receivers (RX). Further, transceiver 168 may includecircuitry to communicate information, data, transactions and so forth inaccordance with one or more standards, such as the WiGig/802.11adStandards. Further, antenna 167 may include a dipole antenna, an antennaarray, an internal antenna, a one pole antenna, or the like. Accordingto embodiments, STA B 170, STA C 180, and STA D 190 may include asimilar or the same architecture as STA A 160 and the description of STAA 160 may be relevant to the to STA B 170, STA C 180, and STA D 190 aswell.

According to embodiments, each pair of stations (e.g., STA A and STA B,STA C and STA D) may configure its antennas (e.g., antenna 138) for adirect link (e.g., direct links 142 and 144) establishment. A pair ofstations may include a Source station and a Destination station, forexample STA A 160 may be a Source station and STA B 170 may be aDestination station. In another example, STA D 190 may be a Sourcestation and STA C 180 may be a Destination station. A pair of stationsmay have an agreed up transaction session start time for eachtransaction session and may have a time reservation for protected timeto communicate during the transaction sessions by using Request To Send(RTS)/Clear To Send (CTS) handshaking.

In some embodiments, the time reservation may be allocated by thestation that is operating as the Source station for communicating atransaction to the corresponding Destination station by communicating aRTS frame or a CTS frame including information in a duration field. Theinformation in the duration field of a frame may include a timereservation value to reserve time for a transaction session for theSource station and the Destination station. The information in theduration field of the frame may also be used by interfering stationsthat want to communicate at the same time or during overlappingtransaction sessions. For example, an interfering station may receive aframe during a listening period indicating the establishment of atransaction session between a Source station and a Destination station.The interfering station may use the information and time reservationvalue in the duration field of the frame to set a network allocationvector (NAV) timer (not shown).

By way of an example, STA A 160 may be a Source station, which mayconfigure antennas 167 to establish a direct link 142 with a Destinationstation (e.g., STA B 170). The processor component 162 may configureantennas 167 to establish the direct link 142 by executing instructionsstored in memory component 164, for example. The processor component 162may also control transceiver 168 and beamformer 166 to set antenna'selements 167 according to a communication and antenna scheme. Althoughit should be understood that embodiments of the invention are notlimited to this example.

Furthermore, when the direct link 142 is established, STA A 160 and STAB 170 may enter a listening mode during a listen period to determine ifany other devices are communicating on the same channel and mayinterfere with a transaction. For example, STA C 180 and STA D 190 mayhave an established direct link 144 and may communicate a frame duringthe listen period for STA A 160 and STA B 170. STA A 160 may receive theframe and the processor component 162 may update a NAV timer with a timereservation value in a duration field of the frame. The value mayreserve time for a transaction session for STA C and STA D tocommunicate within. The NAV timer may count down and may be locked at avalue zero, for example. Once the NAV timer researches the value zero,STA A 160 and STA B 170 may communicate a transaction during atransaction session. In some instances, the processor component 162 mayreset the NAV timer when a frame, such as a contention-free end (CF-End)frame, containing a medium access control (MAC) address that may beequal to the MAC address in the frame that asserts the NAV timer valueincluding a truncation time. The processor component 162 may reset theNAV timer to zero when a frame is received indicating a truncation of atransaction session prior to the expiration of the original timereservation.

In some embodiments, the processor component 162 may not receive a framehaving a time reservation value during the listen period and may begin atransaction session to communicate a transaction between STA A 160 andSTA B 170 immediately after the listen period. The processor component162 may reserve time for the transaction session by communicate a frame,such as an CTS frame or an RTS frame, prior to communicate informationand data in a transaction. In this example, STA C 180 and/or STA D 190,whichever is in range, may receive the frame during a listening periodand set their own NAV timers to adjust the start of the transactionsession until STA A 160 and STA B 170 have completed communicated atransaction.

As similarly as discussed, STA A 160 and/or STA B 170 may communicate aframe indicating the truncation of their transaction session prior toexpiration of the original time reservation. STA C 180, STA D 190, orboth may receive the frame and may conduct a transaction during anadjusted transaction session. As will be discussed in more detail below,the stations may use the truncation time to adjust start times forsubsequent transaction sessions.

FIG. 2 illustrates an exemplary embodiment of a timing diagram 200 forstations communicating during transaction sessions. In the exemplarytiming diagram 200, two PBSSs may be established, a first PBSS includesSTA A as a Source station and STA B as a Destination station and asecond PBSS includes STA D as a Source station and STA C as aDestination station.

Timing diagram 200 illustrates the second PBSS including STA C and STA Dexiting a standby mode where at least transceivers of the stations arein a low power or powered off state at line 202. The stations, STA C andSTA D, may exit the standby mode at a determined transaction sessionstart time and may enter a listening mode during a listen period 206before communicating a transaction during a transaction session having atransaction session period 246. If STA C and STA D do not receive aframe indicating that a channel for a transaction is in use by otherdevices, STA C and STA D may communicate a transaction during theintended transaction session period 246. However, if STA C and/or STA Dreceive a frame reserving time to communicate on the channel, STA C andSTA D may set NAV timers based on a time reservation value in the frame.The stations, STA C and STA D, will wait until the expiration of theirNAV timers to conduct a transaction or until they receive another frametruncating the transaction session for the other devices.

The timing diagram 200 of FIG. 2 shows STA A communicating a CTS frame204 having a value to reserve time or a duration 210 for a transactionsession between STA A and STA B. STA C, STA D, or both may receive theCTS frame 204 communicated by STA A. In the illustrated embodiment, FIG.2 only shows STA D receiving the sent CTS frame 204 as received CTSframe 208. STA D may use the value in the CTS frame 208 to set its NAVtimer to a NAV time 212 and communicate the value to STA C for it to seta NAV timer to the NAV time 212. In this example, STA C may be out ofrange to receive the CTS frame 204, however, various embodiments are notlimited in this manner and both stations may receive the CTS frame 204.

During the transaction session between STA A and STA B, STA A maycommunicate a transaction to STA B, the transaction may includeinformation and data in any number of frames, such as an aggregate mediaaccess control protocol data unit (A-MPDU) 214 or any other type of unitthat may include information and data. In response to receiving theA-MPDU 214, STA B may communicate a block acknowledgement (BA) 216. Invarious embodiments, STA A and STA B may communicate any amount ofinformation during the duration 210 of the transaction session. In someembodiments, STA A or STA B may communicate a frame, such as a CF-Endframe having a truncation time, to truncate the transaction sessionprior to the expiration of the NAV time 212 originally allocated for thetransaction session. For example, FIG. 2 illustrates STA A communicatinga CF-End frame 218 including a value to truncate the transactionsession. The value may include zero time to immediately truncate thetransaction session or non-zero time to initiate a CF-End frametransmission of the STA B. The time is of the size of the CF-End frameplus a short interframe space (SIFS). If the value of the duration fieldof the received CF-End frame is not equal to zero the STA B communicatesa CF-End frame 220 as an acknowledgement to receiving the CF-End frame218 from STA A.

In some embodiments, STA C, STA D, or both may receive at least one ofthe CF-End frames communicated by STA A and STA B. For example, timingdiagram 200 illustrates STA D receiving the CF-End frame 222communicated by STA A. As previously mentioned, the CF-End frame 222 mayinclude a value, such as a truncation time 224, to truncate thetransaction session between STA A and STA B. STA D may use the value toreset its NAV timer and shift transaction session start times forsubsequent transaction sessions between STA D and STA C.

More specifically, STA D may use the value in the CF-End frame 222 todetermine a delta network allocation vector (NAV) time 226 to use whenshifting transaction session start time for at least one subsequenttransaction session. The STA D may determine the delta NAV time 226based on difference between end of the received CF-End frame (222) and acurrent transaction session start time (x) at line 202 plus value inCF-End frame (222), where x may be any positive integer. The delta NAVtime 226 may be added to a subsequent preset or predeterminedtransaction session time (x+1) to determine a new transaction sessiontime (x+1) for a subsequent transaction session between STA C and STA D.Various embodiments are not limited to this example, and a delta NAVtime may be based on the difference between any frame having a value totruncate a transaction session and a transaction session start time fora different transaction session between different devices.

In addition, once the transaction session between STA A and STA B hasended, both STA A and STA B may enter a standby mode putting thestations into a power saving state. Further, STA D may receive theCF-End 222 and may start the communicating a transaction during thetransaction session period 248 by first waiting for a random back off(BOFF) period 228 and then communicating a RTS frame 230 having a valueto reserve time for the transaction session. STA C may receive the RTSframe 230 and respond with a CTS frame 232 also including a value toreserve time for the adjusted transaction session. In this example, STAsA and B will be in a standby mode and will not receive the RTS frame 230and the CTS frame 232 send by the STAs D and C, respectively.

STA D may communicate information and data to STA C in one or moreframes, such as A-MPDU 234 and STA C may response with BA 236. In someembodiments, STA C may also send information and data to STA D in one ormore frames, such as A-MPDU 238 and STA D may respond with BA 240 duringthe adjusted transaction session. As similarly discussed above, STA Cand STA D may communicate any amount of information and data in anynumber of frames during the adjusted transaction session within thereserved time period.

The stations, STA C and STA D, may wait for the reserved time period toexpire or may send CF-End frames to truncate the adjusted transactionsession and enter a standby mode of operation. For example and asillustrated in timing diagram 200, STA D communicates CF-End frame 242having a value to truncate the transaction session and STA Ccommunicates CF-End frame 244 in response to CF-End frame 242 and alsoincluding a value to truncate the transaction session. The STAs C and Dmay enter the standby mode of operation until the start of the nexttransaction session based on the new transaction session start time(x+1). In various embodiments, the intended transaction session period246 may be the period between transaction sessions previously determinedand negotiated by STAs C and D. The adjusted transaction session period248 may be the period between transaction sessions based on the deltaNAV time 226 determined by STA D.

As will be discussed in more detail below with respect to FIGS. 3A and3B an adjustment may be made to a transaction session start time foreach subsequent transaction session until there is no overlapping withinterfering stations. Further, adjusting the transaction session starttimes may be advantageous for stations because they may remain in astandby mode of operation for longer periods of time conserving morepower. Viewed differently, stations may spend less time in a fullyactive state while a NAV timer is counting down during transactionsessions of interfering devices waiting to communicate a transaction.Thus, adjusting the start times of transaction sessions based on a deltaNAV time provides a more efficient scheduling scheme for transactionsessions.

FIG. 3A illustrates an exemplary embodiment of a second timing diagram300 of stations communicating during transaction sessions. Morespecifically, timing diagram 300 shows the station pair A and Bcommunicating transactions 301, 307 and 313 on line 302 and the stationpair C and D communicating transactions 305, 309 and 315 on line 304.Each of the transactions may be communicated during a transactionsession and the time between each of the transactions may be atransaction session period. Furthermore, each transaction may includeany number of communicated frames between the stations. For example, oneor more frames, such as a CTS frame, an A-MPDU frame, a BA frame, aCF-end frame, and so forth may be communicated for a transaction.

Timing diagram 300 shows STAs C and D shifting a transaction sessionstart time for a subsequent transaction based on a measured delta NAVtime between a transaction session start time at line 306 and the end ofthe transaction 301 at line 310. As similarly discussed above withrespect to FIG. 2, STAs C and D may determine the delta NAV time basedon a difference between a transaction session start time for STAs C andD (line 306) and a truncation time of a transaction session between STAsA and B (line 310). The truncation may be indicated in a frame sent bySTA A and/or STA B at the end of transaction 301. In this illustratedembodiment, STAs C and D only need to make one adjustment or shift to atransaction session start time and each subsequent transaction 309, 313and so forth, will have the transaction session start times that do notoverlap with interfering stations because STAs A and B and STAs C and Dhave the same transaction session period length. As will be discussed inmore detail with respect to FIG. 3B, additional adjustments may need tobe made if the stations do not have the same transaction session periodlength.

In timing diagram 300, the start of transaction 305 may be delayed untiltransaction 301 completes, as illustrated by arrow 303 showing a shiftof the start of transaction 305. Moreover, the start of the nexttransaction session for STAs C and D to communicate subsequenttransaction 311 may also be shifted or adjusted from line 316 to 318 asillustrated by arrow 309. The adjustment is based on the delta NAV timepreviously determined. More specifically, the delta NAV time may beadded to a preset, determined, or predetermined transaction sessionstart time for a subsequent transaction for STAs C and D to determine anew transaction session start time. As such, STAs C and D may remain ina standby mode longer while transaction 307 between STAs A and B iscompleted, for example. In timing diagram 300, no further adjustments orshifts are needed because the AB transaction session period 308 is equalto the CD transaction session period 312 and shifted transaction sessionperiod 314.

FIG. 3B illustrates an exemplary embodiment of a third timing diagram350 of stations communicating during transaction sessions. Morespecifically, timing diagram 300 shows the station pair A and Bcommunicating transactions 351, 357 and 365 on line 352 and the stationpair C and D communicating transactions 355, 363 and 369 on line 304. Inthis exemplary embodiment, STAs A and B and STAs C and D have differenttransaction session period lengths. For example, the AB transactionsession periods 356 and 366 are longer than the CD transaction sessionperiods 362 and 374. In some instances, when the transaction sessionperiods of different station pairs are not the same length, more thanone adjustment or shift may be needed such that transaction session donot overlap.

As similarly discussed above, timing diagram 350 shows STA C and STA Dtransaction session starting at line 358 during transaction 351communication between STAs A and B. STAs C and D must wait untiltransaction 351 is completed before transaction 355 may be communicatedbetween STAs C and D as indicated by arrow 353. Once transaction 351 iscomplete, STAs C and D may communicate transaction 355.

However, while STAs C and D are waiting for transaction 351 to complete,significant processing power and battery life may be consumed. Thus,STAs C and D may determine a delta NAV time based on the differencebetween the transaction start time at line 358 and the end of thetransaction 351 at line 360. The delta NAV time may be used to shift thetransaction session start time for a subsequent transaction by addingthe delta NAV time to a preset, determined or predetermined transactionsession start time for a subsequent transaction. For example, delta NAVtime (1) may be added to CD transaction session start time (N+1) todetermine a new transaction session start time for STAs C and D, asillustrated by arrow 359.

In some embodiments, station pairs may have different transactionsession period lengths. For example, FIG. 3B shows STAs A and B having alonger transaction session period length than STAs C and D. In thiscase, STAs C and D may exit the standby mode while transaction 357 isbeing communicated even after the CD transaction session start time fortransaction 363 has been shifted as indicated by arrow 359. Thus,transaction 363 may be shifted again as indicated by arrow 361.

In addition, a delta NAV time (2) determination may be made by STAs Cand D based on the difference between the new transaction session starttime for the subsequent transaction 363 at line 370 and the end oftransaction 357 between STAs A and B at line 372. The delta NAV time (2)may be added to the transaction session start time for subsequenttransaction 369 to determine a new subsequent transaction session starttime for the transaction 369 as indicated by arrow 367 and the CDTransition Session Period (374) can be extended by delta NAV. In thiscase, the next subsequent transaction between STAs C and D will likelynot overlap and, as such, the STAs C and D may realize power and batterylife savings. However, since the transaction session periods are not thesame between STAs A and B and STAs C and D, additional shifts oradjustments may be required for subsequent transaction. Variousembodiments are not limited in this manner.

FIG. 4 illustrates an exemplary embodiment of a first logic flow diagram400 to communicate transactions in a wireless network. Logic flow 400may be performed by any type of computing system or computing device,such as a station and is discussed with reference to station 160 of FIG.1B.

In various embodiments, a station 160 including its components may exita standby mode of operation at block 402. In the standby mode ofoperation, one or more components of the station 160 may be in a powersaving state. For example, transceivers 168 may be powered off and/or ina low power state where a minimal amount of power is being consumed.When the station 160 exits the standby mode of operation, transceivers168 may be put into a full power state to communicate information withother devices.

At block 404, the station 160 may enter a listening period to determinewhether other devices are communicating on the same channel or frequencythat may interfere with a communicated transaction. Further, the station160 and, in particular, the processor component 162 may determinewhether other devices are communicated based on received information ortransactions. For example, the stations 160, via transceiver 168, mayreceive a frame, such as a RTS frame or CTS frame, during the listeningperiod indicating that other devices are communicating on a channel inwhich the station 160 desires to communicate on. In some embodiments,the station 160 may not receive information during the listen period andthe channel may be free to communicate on. In this case, the station 160may communicate a transaction with another device or station at block420.

More specification, the station 160 may be coupled with another deviceor station in an ad-hoc or peer-to-peer arrangement, such as a PBSS andmay communicate a transaction during a transaction session with theother station. The transaction may including communicating one or moreframes having information and data with the other station.

If the station 160 including the processor component 162 determine thatother devices are communicating on a desired channel during the listenperiod at block 406, the processor component 162 may wait to communicatethe transaction and set a NAV timer at block 408. For example and insome embodiments, the station 160 may receive a RTS frame or a CTS frameincluding a time reservation to reserve time to conduct a transactionbetween the other devices. The station 160 may use the time reservationto set a NAV timer to countdown from. While the NAV timer is countingdown, the station 160 may not communicate or conduct a transaction. TheNAV timer may countdown to zero, and only after zero has been reachedwill the station 160 proceed with communicating a transaction withanother station.

More specifically, the NAV timer may be decremented by a unit of one atblock 410. Further, the station 160 may determine at block 412 whether aframe including truncation information including a truncation time hasbeen received. For example, the station may receive a CF-End framehaving a truncation time in a duration field to end the transactionbetween the other devices before the expiration of the NAV timer.

If the station 160 does receive a frame with truncation information atdecision block 412, the station 160 may determine a delta NAV time toshift a transaction session start time for a subsequent transaction atblock 416 and may shift a transaction session start time at block 418.More specifically, the station 160, and in particular, the processorcomponent 162 may determine a difference between when the station 160exited the standby mode of operation, i.e. a transaction session starttime, and a truncation time. The difference or delta NAV time may beadded to a predetermined and negotiated transaction session start timefor a subsequent transaction.

The processor component 162 may use the delta NAV time to shift at leastone transaction session start time for a subsequent transaction at block418. For example, the station 160 may conduct transactions on a periodicbasis based on a transaction session interval period and the processorcomponent 162 may shift the predetermined or preset transaction sessionstart time for the next transaction session by the delta NAV. Variousembodiments are not limited in this manner.

If the station 160 does not receive a frame truncating the transactionbetween the other devices at decision block 412, the station 160 maydetermine whether the NAV timer has expired or reached zero at block414. In some embodiments, the station 160 may determine if the NAV timerhas expired prior to checking if it has received a frame havingtruncation information. Various embodiments are not limited in thismanner and the blocks illustrated in FIG. 4 are not limited to aparticular order.

If the NAV timer has not expired at block 414, blocks 410 through 414may be repeated until the NAV timer reaches zero or a frame truncatingthe transaction is received. Once the NAV timer has expired or a frametruncating the transaction has been received, at block 420 the station160 may communicate a transaction via processor component 162,transceiver 168, beamformer 166 and antenna array 167 with anotherdevice or station, as previously discussed. Once the transaction iscomplete, the station 160 may enter a standby mode until the nexttransaction session is to occur at block 422.

FIG. 5 illustrates an embodiment of fourth timing diagram 500 tocommunicate a transaction session start time. More specifically, FIG. 5shows STA D and STA C during a transaction session where a transactionincluding an RTS frame, CTS frame, an A-MPDU frame and so forth arecommunicated between STA C and STA D. At the end of the transaction, STAC, STA D, or both may communicate a CF-End frame. As previouslydiscussed, the CF-End frame may be used to communicate a truncation of atransaction session to the intended receiving device and other deviceswaiting to communicate on the same channel the transaction is occurringon. For example, timing diagram 500 shows STA D communicating CF-Endframe 506 to STA C to indicate the end of a transaction session.

In some embodiments, the stations may communicate a transaction sessionstart time for the next transaction session. The transaction sessionstart time for the next transaction session may be a new transactionsession start time based on a calculated delta NAV time, as previouslydiscussed above and may be communicated between stations bycommunicating a Grant frame followed by a CF-End frame. As will bediscussed in detail with respect to FIG. 6, a Grant frame may include anumber of fields including a duration field having duration informationand a dynamic allocation information field having allocation durationinformation. Further and as will be discussed below in FIG. 7, TheCF-End frame may also having a number of fields including a durationfield having duration information, e.g. a truncation time for the CF-Endframe. The information in the Grant frame and the CF-End frame may beused to determine the transaction session start time for the nexttransaction session. More specifically, Equation 1 illustrates oneexemplary embodiment for determining a transaction session start timebased on the information in a Grant frame and a CF-End frame.

(1) transaction session start time=end of Grant frame receivingtime+duration information (Grant frame)−Grant allocation durationinformation, where:

the duration information (Grant frame) is a time to communicateremaining Grant frame(s) if required+interframe spacing (IFS or SIFS)for each of the Grant frames+time to transmit one or two CF-Endframes+SIFS if two CF-End frames are sent+the allocation duration; and

the allocation duration information is a time allocated for atransaction session.

By way of example and as illustrated in FIG. 5, STA D may communicateGrant frame 502 during the transaction session followed by a CF-Endframe 504 to truncate the transaction session. The Grant frame 502 mayinclude duration information 514 in a duration field and allocationinformation 516 in an allocation duration field. As previouslydiscussed, the duration information 514 may be an amount of time tocommunicate remaining Grant frame(s) if required, IFS(s) and/or SIFS(s)and the allocation duration 516. The allocation duration 516 may be theamount of time allocated to communicate a transaction during atransaction session.

The CF-End frame may include duration information 510 in a durationfield which is an amount of time until the truncation time 512. In someinstances, the duration information 510 may be zero if there is no timebetween the end of a CF-End frame and a truncation time. By usingequation 1, both STA D and STA C may calculate the transaction sessionstart time 518 for the next transaction based on the durationinformation 514, the allocation information 516, duration information510, a time to communicate CF-End frame 506 and a SIFS time 504 usingequation 1 above.

In some embodiments, stations may communicate a transaction sessionstart time for the next transaction at the end of current transactionsession. However, in the same or other embodiments, a transactionsession start time may only be communicated when there shift oradjustment made based on a delta NAV calculation. Various embodimentsare not limited in this manner.

FIG. 6 illustrates an exemplary embodiment of a Grant frame 600 that maybe communicated during a transaction and include information todetermine a transaction session start time. The Grant frame 600 mayinclude a number of fields having information in accordance with one ormore standards, such as IEEE 802.1 lad. For example, Grant frame 600 mayinclude a frame control field 602, a duration field 604, a receiveaddress (RA) field 606, a transmit address (TA) field 608, a dynamicallocation information field 610, a beamforming (BF) control field 612,and a frame check sequence (FCS) field 614.

The frame control field 602 may including control information for thegrant frame 600, the duration field 604 may include a time to transmitany remaining Grant frame(s) if required, including required IFS's, andthe allocation duration. The RA field 606 contains the medium accesscontrol (MAC) address for the station receiving the Grant frame 600 andthe TA field 608 contains the MAC address of the station that istransmitting the Grant frame 600. The BF control field 612 contains anumber of sub-fields having information for beamforming training, linkadaptation, calibration control and feedback request information. TheFCS field 614 contains information to conduct error detection for theGrant frame 600 by the receiving station.

The dynamic allocation information field 610 includes a number ofsub-fields as illustrated in FIG. 6. More specifically, the dynamicallocation information field 610 may include a traffic identifier field630 which includes information to identify the TC or TS for theallocation request or grant, an allocation type field 632 containsinformation to define the channel access mechanism during theallocation. The dynamic allocation information field 610 may alsoinclude a source AID field 634 containing information to identify thestation that is the source of the allocation and a destination AID field636 containing information to identify the station that is thedestination of the allocation.

The allocation duration field 638 contains a requested duration for atransaction. In some embodiments, the requested duration may be inmicroseconds with possible range values from 0 to 32,767 for atransaction session allocation and 0 to 65,535 for a CBAP allocation. Insome embodiments, a value of 0 in the allocation duration field 638 mayindicate that a station can transmit one PDDU followed by any relevantacknowledgement plus one RTS/DMG CTS handshake.

FIG. 7 illustrates an exemplary embodiment of a CF-End frame 700 inconcordance with 802.11 that may be communicated during a transactionand include information to determine a transaction session start time.The CF-End frame 700 may include a number of fields having informationin accordance with one or more standards, such as IEEE 802.11. Forexample, the CF-End frame 700 may include a control field 702, aduration field 704, a receive address (RA) field 706, a transmit address(TA) field 708 and a frame check sequence (FCS) field 710.

The control field 702 may include control information for the CF-Endframe 700, the RA field 706 may contain the broadcast group address or aMAC of the intended receiving station, the TA field 708 may include theaddress of the station contained in an AP or MAC address of the stationtruncating the transaction session, and the FCS field 710 may includeinformation to conduct error detection for the CF-End frame 700 by thereceiving station. The duration field 704 may contain durationinformation indicating an amount of time until the truncation time orthe time required to complete a CF-End truncation sequence, i.e. atruncation time. As previously discussed, the duration information maybe used by a receiving device to determine a transaction session starttime. Various embodiments are not limited in this manner.

FIG. 8A illustrates an exemplary embodiment of a logic flow 800 forperforming a transaction session and communicating a transaction sessionstart time. Logic flow 800 may be performed by any type of computingsystem, computing device, station and so forth. For example, logic flow800 may be performed by a station conducting a transaction session withanother station that initiated the transaction session, such as STA C inFIGS. 1B, 2 and 5.

At block 802 a station may exit a standby mode of operation where one ormore components are in a power saving state to conserve battery life andpower. In some embodiments, the station may exit the standby mode at atransaction session start time that may be based on a negotiated time bythe stations and may be preset, predetermined or determined. In someembodiments, the transactions session start time may have beenpreviously communicated to the station via a Grant frame followed by aCF-End frame and may take into account a delta NAV shift based on otherdevices communicating on a same channel.

The station may communicate a transaction during a transaction sessionat block 804. As previously discussed, the transaction may include thesending and receiving of a number of frames, such as an RTS frame, a CTSframe, an A-MPDU frame, and so forth. In some embodiments, the stationmay communicate the transaction after a listen period and adetermination has been made that no other devices are interfering on asame channel for communication.

At block 806, the station may receive a Grant frame having informationincluding duration information in a duration field and allocationduration information in a dynamic allocation information field from thestation that initiated the transaction session. Further and at block808, the station may receive a CF-End frame having information includingduration information, i.e. a truncation time in a duration field. Insome embodiments, the CF-End frame may be the next frame received afterthe Grant frame without any intervening frames. Further, the CF-Endframe may be received after an IFS or a short interframe space (SIFS).Various embodiments are not limited in this manner.

In some embodiments, the station may send a CF-End frame at optionalblock 810 if it is allowed by the peer STA. The CF-End frame sent by thestation and may also include duration information equal to zero, i.e. atruncation time in a duration field. However, in various embodiments,the station may not send a CF-End frame at block 810 and the logic flow800 may proceed to determining a transaction session start time at block812. The station may determine the transaction session start time forthe next transaction based on the information in the Grant framereceived from the other station.

At block 814, the station may enter a standby mode operation until thenext transaction session is to occur. More specifically, the station mayenter a standby mode until the transaction session start time determinedat block 812. In various embodiments, blocks 802 through 814 may repeatany number of times to conduct one or more transaction duringtransaction sessions and may occur on a periodic or semi-period basishaving a transaction session period.

FIG. 8B illustrates an exemplary embodiment of a logic flow 850 forperforming a transaction session and communicating a transaction sessionstart time. Logic flow 850 may be performed by any type of computingsystem, computing device, station and so forth. For example, logic flow850 may be performed by a station initiating and conducting atransaction session with another station, such as STA D in FIGS. 1B, 2and 5.

At block 852 a station may exit a standby mode of operation where one ormore components are in a power saving state to conserve battery life andpower. In some embodiments, the station may exit the standby mode at atransaction session start time that may be based on negotiated time bythe stations. In some embodiments, the transactions session start timemay be been previously communicated to the station via a Grant framefollowed by a CF-End frame and may take into account a delta NAV timeshift based on other devices communicating on a same channel.

In some embodiments, the station may enter a listening period anddetermine if other devices are communicating on a same and at optionalblock 854, the station may determine a delta NAV time to shift starttimes for one or more subsequent transaction sessions. If no otherdevices are communicating on the same channel in which the station is tocommunicate on, the station will not determine a delta NAV at optionalblock 854. At block 856, the station may communicate a transactionduring a transaction session with another station. During thetransaction, the stations may communicate one or more frames havinginformation.

At block 858, the station may determine a transaction session start timefor the next transaction and transaction session. If a delta NAV wasdetermined at block 854, the station may determine a transaction startsession start time, by shifting a predetermined, preset, or determinedtransaction session start time for a subsequent transaction session bythe delta NAV time or to use adjusted Transaction Session Period. Thestation may communicate the transaction session start time, bycommunicating a Grant frame at block 860 and a CF-End frame at block862. The Grant frame may include duration information and allocationduration information and the CF-End frame may include durationinformation to allow CF-End transmission by the initiated station. Thereceiving station may use this information to determine the transactionsession start time, as previously discussed.

If the receiving station sends a CF-End frame, the station may receive aCF-End frame at optional block 864. The station may enter a standby modeat the end of the transaction at block 866. In various embodiments, thestation may remain in the standby mode of operation until thetransaction session start time when another transaction session is tooccur. Blocks 852 through 866 may be repeated any number of times andvarious embodiments are not limited in this manner.

FIG. 9 illustrates one embodiment of a logic flow 900. The logic flow900 may be representative of some or all of the operations executed byone or more embodiments described herein. For example, the logic flow900 may illustrate operations performed by systems 100, 150, stations160, 170, 180 and 190, and so forth. In the illustrated embodiment shownin FIG. 9, the logic flow 900 may include initiating a transactionsession at a transaction session start time to communicate a transactionbetween a first device and a second device at block 905. The transactionsession start time may be predetermined or negotiated between the firstdevice and the second device to communicate a transaction. Further, thefirst device and second device may conduct a number of transactionsession to communicate transaction on a periodic, semi-periodic, ornon-period basis. For example, the time between two transaction sessionstart times may be a transaction session period.

Further, the first device and the second device may communicateinformation in one or more frames during the transaction session as atransaction. For example, the first device and second device maycommunicate frames, such as an RTS frame, a CTS frame, MPDU frame, anA-MPDU, a CF-End frame, Grant frame, or any other type of frame duringthe transaction session.

In some embodiments, the first device and second device may enter alisten period upon the initiation of the transaction to determinewhether one or more other devices are communicating on a same channel inwhich the transaction is to occur on. Logic flow 900 may also includereceiving a first frame comprising information indicating an occurrenceof another transaction session between other devices and a timereservation for the other transaction session at block 910. For example,the first device or second device may receive a CTS frame or a RTS framehaving time information to receive a time period for other devices toconduct transaction to and to prevent the first device and second devicefrom communicating during this time period as not to cause interference.

The first device and the second device may set a NAV timer uponreceiving the first frame based on the time reservation. The NAV timermay countdown from a time based on the time reservation until it reacheszero. However, various embodiments are not limited in this manner andthe NAV timer may count up from zero until the time reservation isreached. While the NAV timer is counting, the first device and thesecond device may not communicate frames.

In some instances, the time reservation may be truncated. Morespecifically, the logic flow 900 may include receiving a second framecomprising second information indicating a truncation of the othertransaction session at a truncation time and before an expiration of thetime reservation at block 915. One or both of the other devices maydetermine that the transaction has completed before the expiration ofthe time reservation and may indicate to the first and/or second devicethat they are free to communicate on the channel by communicate a framehaving a truncation time. For example, one or both of the other devicesmay communicate a CF-End frame having a truncation time indicating atime to truncation the other transaction session. In some embodiments,the truncation time may be zero immediately release the channel forcommunication. However, various embodiments are not limited in thismanner and the truncation time may be any time in the future, inmicroseconds for example, indicating when the transaction session iscomplete.

For future transaction sessions, the first and second device may adjustor shift a transaction session start time such that they may spend moretime in a standby mode of operation and a low power state. When thefirst and second devices are waiting for the other devices to finishtheir transaction session a significant amount of power may be used.Thus, battery life extended by shifting or adjusting subsequenttransaction session start time. In some embodiments, logic flow 900 mayinclude shifting a subsequent transaction session start time for atleast one subsequent transaction session between the first device andthe second device based on a difference between the transaction sessionstart time and the truncation time at block 920. In particular, thedifference between the transaction session start time and the truncationtime may be a delta NAV time that may be added to a predetermined ornegotiated subsequent transaction session star time causing the firstand second devices to remain in the standby mode longer. The TransactionSession Period may be adjusted to be kept even no delta NAV is observedin the current transaction.

FIG. 10 illustrates an embodiment of an exemplary computing architecture1000 suitable for implementing various embodiments as previouslydescribed. In one embodiment, the computing architecture 1000 mayinclude or be implemented as part of or system 100, 150 or any of thedevices and stations discussed above.

As used in this application, the terms “system” and “component” areintended to refer to a computer-related entity, either hardware, acombination of hardware and software, software, or software inexecution, examples of which are provided by the exemplary computingarchitecture 1000. For example, a component can be, but is not limitedto being, a process running on a processor, a processor, a hard diskdrive, multiple storage drives (of optical and/or magnetic storagemedium), an object, an executable, a thread of execution, a program,and/or a computer. By way of illustration, both an application runningon a server and the server can be a component. One or more componentscan reside within a process and/or thread of execution, and a componentcan be localized on one computer and/or distributed between two or morecomputers. Further, components may be communicatively coupled to eachother by various types of communications media to coordinate operations.The coordination may involve the uni-directional or bi-directionalexchange of information. For instance, the components may communicateinformation in the form of signals communicated over the communicationsmedia. The information can be implemented as signals allocated tovarious signal lines. In such allocations, each message is a signal.Further embodiments, however, may alternatively employ data messages.Such data messages may be sent across various connections. Exemplaryconnections include parallel interfaces, serial interfaces, and businterfaces.

The computing architecture 1000 includes various common computingelements, such as one or more processors, multi-core processors,co-processors, memory units, chipsets, controllers, peripherals,interfaces, oscillators, timing devices, video cards, audio cards,multimedia input/output (I/O) components, power supplies, and so forth.The embodiments, however, are not limited to implementation by thecomputing architecture 1000.

As shown in FIG. 9, the computing architecture 1000 includes aprocessing unit 1004, a system memory 1006 and a system bus 1008. Theprocessing unit 1004 can be any of various commercially availableprocessors, such as those described with reference to the processorcomponent 102 shown in FIG. 1.

The system bus 1008 provides an interface for system componentsincluding, but not limited to, the system memory 1006 to the processingunit 1004. The system bus 1008 can be any of several types of busstructure that may further interconnect to a memory bus (with or withouta memory controller), a peripheral bus, and a local bus using any of avariety of commercially available bus architectures. Interface adaptersmay connect to the system bus 1008 via a slot architecture. Example slotarchitectures may include without limitation Accelerated Graphics Port(AGP), Card Bus, (Extended) Industry Standard Architecture ((E)ISA),Micro Channel Architecture (MCA), NuBus, Peripheral ComponentInterconnect (Extended) (PCI(X)), PCI Express, Personal Computer MemoryCard International Association (PCMCIA), and the like.

The computing architecture 1000 may include or implement variousarticles of manufacture. An article of manufacture may include acomputer-readable storage medium to store logic. Examples of acomputer-readable storage medium may include any tangible media capableof storing electronic data, including volatile memory or non-volatilememory, removable or non-removable memory, erasable or non-erasablememory, writeable or re-writeable memory, and so forth. Examples oflogic may include executable computer program instructions implementedusing any suitable type of code, such as source code, compiled code,interpreted code, executable code, static code, dynamic code,object-oriented code, visual code, and the like. Embodiments may also beat least partly implemented as instructions contained in or on anon-transitory computer-readable medium, which may be read and executedby one or more processors to enable performance of the operationsdescribed herein.

The system memory 1006 may include various types of computer-readablestorage media in the form of one or more higher speed memory units, suchas read-only memory (ROM), random-access memory (RAM), dynamic RAM(DRAM), Double-Data-Rate DRAM (DDRAM), synchronous DRAM (SDRAM), staticRAM (SRAM), programmable ROM (PROM), erasable programmable ROM (EPROM),electrically erasable programmable ROM (EEPROM), flash memory, polymermemory such as ferroelectric polymer memory, ovonic memory, phase changeor ferroelectric memory, silicon-oxide-nitride-oxide-silicon (SONOS)memory, magnetic or optical cards, an array of devices such as RedundantArray of Independent Disks (RAID) drives, solid state memory devices(e.g., USB memory, solid state drives (SSD) and any other type ofstorage media suitable for storing information. In the illustratedembodiment shown in FIG. 9, the system memory 1006 can includenon-volatile memory 1010 and/or volatile memory 1012. A basicinput/output system (BIOS) can be stored in the non-volatile memory1010.

The computer 1002 may include various types of computer-readable storagemedia in the form of one or more lower speed memory units, including aninternal (or external) hard disk drive (HDD) 1014, a magnetic floppydisk drive (FDD) 1016 to read from or write to a removable magnetic disk1018, and an optical disk drive 1020 to read from or write to aremovable optical disk 1022 (e.g., a CD-ROM or DVD). The HDD 1014, FDD1016 and optical disk drive 1020 can be connected to the system bus 1008by a HDD interface 1024, an FDD interface 1026 and an optical driveinterface 1028, respectively. The HDD interface 1024 for external driveimplementations can include at least one or both of Universal Serial Bus(USB) and IEEE 1394 interface technologies.

The drives and associated computer-readable media provide volatileand/or nonvolatile storage of data, data structures, computer-executableinstructions, and so forth. For example, a number of program modules canbe stored in the drives and memory units 1010, 1012, including anoperating system 1030, one or more application programs 1032, otherprogram modules 1034, and program data 1036. In one embodiment, the oneor more application programs 1032, other program modules 1034, andprogram data 1036 can include, for example, the various applicationsand/or components of the system 105.

A user can enter commands and information into the computer 1002 throughone or more wire/wireless input devices, for example, a keyboard 1038and a pointing device, such as a mouse 1040. Other input devices mayinclude microphones, infra-red (IR) remote controls, radio-frequency(RF) remote controls, game pads, stylus pens, card readers, dongles,finger print readers, gloves, graphics tablets, joysticks, keyboards,retina readers, touch screens (e.g., capacitive, resistive, etc.),trackballs, trackpads, sensors, styluses, and the like. These and otherinput devices are often connected to the processing unit 1004 through aninput device interface 1042 that is coupled to the system bus 1008, butcan be connected by other interfaces such as a parallel port, IEEE 1394serial port, a game port, a USB port, an IR interface, and so forth.

A monitor 1044 or other type of display device is also connected to thesystem bus 1008 via an interface, such as a video adaptor 1046. Themonitor 1044 may be internal or external to the computer 1002. Inaddition to the monitor 1044, a computer typically includes otherperipheral output devices, such as speakers, printers, and so forth.

The computer 1002 may operate in a networked environment using logicalconnections via wire and/or wireless communications to one or moreremote computers, such as a remote computer 1048. The remote computer1048 can be a workstation, a server computer, a router, a personalcomputer, portable computer, microprocessor-based entertainmentappliance, a peer device or other common network node, and typicallyincludes many or all of the elements described relative to the computer1002, although, for purposes of brevity, only a memory/storage device1050 is illustrated. The logical connections depicted includewire/wireless connectivity to a local area network (LAN) 1052 and/orlarger networks, for example, a wide area network (WAN) 1054. Such LANand WAN networking environments are commonplace in offices andcompanies, and facilitate enterprise-wide computer networks, such asintranets, all of which may connect to a global communications network,for example, the Internet.

When used in a LAN networking environment, the computer 1002 isconnected to the LAN 1052 through a wire and/or wireless communicationnetwork interface or adaptor 1056. The adaptor 1056 can facilitate wireand/or wireless communications to the LAN 1052, which may also include awireless access point disposed thereon for communicating with thewireless functionality of the adaptor 1056.

When used in a WAN networking environment, the computer 1002 can includea modem 1058, or is connected to a communications server on the WAN1054, or has other means for establishing communications over the WAN1054, such as by way of the Internet. The modem 1058, which can beinternal or external and a wire and/or wireless device, connects to thesystem bus 1008 via the input device interface 1042. In a networkedenvironment, program modules depicted relative to the computer 1002, orportions thereof, can be stored in the remote memory/storage device1050. It will be appreciated that the network connections shown areexemplary and other means of establishing a communications link betweenthe computers can be used.

The computer 1002 is operable to communicate with wire and wirelessdevices or entities using the IEEE 802 family of standards, such aswireless devices operatively disposed in wireless communication (e.g.,IEEE 802.11 over-the-air modulation techniques). This includes at leastWiFi (or Wireless Fidelity), WiMax, and Bluetooth™ wirelesstechnologies, 3G, 4G, LTE wireless technologies, among others. Thus, thecommunication can be a predefined structure as with a conventionalnetwork or simply an ad hoc communication between at least two devices.WiFi networks use radio technologies called IEEE 802.11x (a, b, g, n,etc.) to provide secure, reliable, fast wireless connectivity. A WiFinetwork can be used to connect computers to each other, to the Internet,and to wire networks (which use IEEE 802.3-related media and functions).

The various elements of the computing device and stations as previouslydescribed with reference to FIGS. 1-10 may include various hardwareelements, software elements, or a combination of both. Examples ofhardware elements may include devices, logic devices, components,processors, microprocessors, circuits, processors, circuit elements(e.g., transistors, resistors, capacitors, inductors, and so forth),integrated circuits, application specific integrated circuits (ASIC),programmable logic devices (PLD), digital signal processors (DSP), fieldprogrammable gate array (FPGA), memory units, logic gates, registers,semiconductor device, chips, microchips, chip sets, and so forth.Examples of software elements may include software components, programs,applications, computer programs, application programs, system programs,software development programs, machine programs, operating systemsoftware, middleware, firmware, software modules, routines, subroutines,functions, methods, procedures, software interfaces, application programinterfaces (API), instruction sets, computing code, computer code, codesegments, computer code segments, words, values, symbols, or anycombination thereof. However, determining whether an embodiment isimplemented using hardware elements and/or software elements may vary inaccordance with any number of factors, such as desired computationalrate, power levels, heat tolerances, processing cycle budget, input datarates, output data rates, memory resources, data bus speeds and otherdesign or performance constraints, as desired for a givenimplementation.

The detailed disclosure now turns to providing examples that pertain tofurther embodiments. Examples one through forty (1-40) provided beloware intended to be exemplary and non-limiting.

In a first example, a system, a station, or an apparatus may includelogic, a portion of which is implemented in hardware, the logic toinitiate a first transaction session with a device at a transactionsession start time, receive information comprising an indication of asecond transaction session with another device, a time reservation forthe second transaction session and a truncation event of the secondtransaction session at a truncation time before expiration of the timereservation, the logic to shift a subsequent transaction session starttime for a subsequent transaction session with the device based on adifference between the transaction session start time and the truncationtime.

In a second example and in furtherance of the first example, a system, astation or apparatus may include logic to cause the apparatus to exit astandby mode of operation at the transaction session start time where atleast a transceiver of the apparatus is in a power saving state.

In a third example and in furtherance of any of the previous examples, asystem, a station or apparatus may include logic to determine a deltanetwork allocation vector time equaling the difference between thetransaction session start time and the truncation time and add the deltanetwork allocation vector time to a preset transaction session starttime to shift the subsequent transaction session start time.

In a fourth example and in furtherance of any of the previous examples,a system, a station or apparatus may include logic to determine whethersubsequent transaction sessions for the apparatus and the device overlapsubsequent transaction sessions for other devices after the subsequenttransaction session start time has been shifted and shift subsequenttransaction session start times until the transaction sessions for theapparatus and the device do not overlap transaction sessions for theother devices.

In a fifth example and in furtherance of any of the previous examples, asystem, a station or apparatus may include logic to communicate atransaction start time using a grant frame and a contention-free end(CF-End) frame, the grant frame comprising a duration field havingduration information and a dynamic allocation information field havingallocation duration information, the CF-End frame comprising a durationfield having duration information for the CF-End frame.

In a sixth example and in furtherance of any of the previous examples, asystem, a station or apparatus may include a memory, a transceivercoupled with at least one antenna, and a processor component to initiatea transaction session at a transaction session start time to communicatea transaction via the transceiver between the apparatus and a device,the transceiver to receive a first frame comprising informationindicating an occurrence of another transaction session between otherdevices and a time reservation to reserve time for the other transactionsession and to receive a second frame comprising second informationindicating a truncation of the other transaction session at a truncationtime and before an expiration of the time reservation, and the processorcomponent to shift a subsequent transaction session start time for atleast one subsequent transaction session between the apparatus and thedevice based on a difference between the transaction session start timeand the truncation time.

In a seventh example and in furtherance of any of the previous examples,a system, a station or apparatus may include the transceiver to receivethe first frame during a listening period of the transaction session todetermine if other devices are communicating on a channel to communicatethe transaction during the transaction session.

In an eighth example and in furtherance of any of the previous examples,a system, a station or apparatus may include the processor component tocause at least the transceiver to exit a standby mode of operation atthe transaction session start time where at least the transceiver of theapparatus is in a power saving state.

In a ninth example and in furtherance of any of the previous examples, asystem, a station or apparatus may include the first frame comprising aclear-to-send (CTS) frame or a request-to-send (RTS) frame communicatedby one of the other devices.

In a tenth example and in furtherance of any of the previous examples, asystem, a station or apparatus may include the second frame comprising acontention-free end (CF-End) frame communicated by one of the otherdevices.

In an eleventh example and in furtherance of any of the previousexamples, a system, a station or apparatus may include the processorcomponent to determine a delta network allocation vector time equalingthe difference between the transaction session start time and thetruncation time and add the delta network allocation vector time to adetermined transaction session start time for the subsequent transactionsession to shift the subsequent transaction session start time.

In a twelfth example and in furtherance of any of the previous examples,a system, a station or apparatus may include the processor component todetermine whether subsequent transaction sessions for the apparatus andthe device overlap subsequent transaction sessions for other devicesafter the subsequent transaction session start time has been shifted andto shift subsequent transaction session start times until thetransaction sessions for the apparatus and the device do not overlaptransaction sessions for other devices.

In a thirteenth example and in furtherance of any of the previousexamples, a system, a station or apparatus may include the processorcomponent to communicate, via the transceiver, a transaction start timeusing a grant frame and a contention-free end (CF-End) frame, the grantframe comprising a duration field having duration information and adynamic allocation information field having allocation durationinformation, the CF-End frame comprising a duration field havingduration information for the CF-End frame.

In a fourteenth example and in furtherance of any of the previousexamples, a system, a station or apparatus may include a housingcomprising the memory, the processor component, the transceiver, andfurther comprising a display; an input/output (I/O) device.

In a fifteenth example and in furtherance of any of the previousexamples, a method may include initiating, by processing circuitry, atransaction session at a transaction session start time to communicate atransaction between a first device and a second device, receiving, bythe processing circuitry, a first frame comprising informationindicating an occurrence of another transaction session between otherdevices and a time reservation to reserve time for the other transactionsession, receiving, by the processing circuitry, a second framecomprising second information indicating a truncation of the othertransaction session at a truncation time and before an expiration of thetime reservation, shifting, by the processing circuitry, a subsequenttransaction session start time for at least one subsequent transactionsession between the first device and the second device based on adifference between the transaction session start time and the truncationtime.

In a sixteenth example and in furtherance of any of the previousexamples, a method may include the first frame received during alistening period of the transaction session to determine if otherdevices are communicating on a channel to communicate the transactionduring the transaction session.

In a seventeenth example and in furtherance of any of the previousexamples, a method may include exiting, by the processing circuitry, astandby mode of operation at the transaction session start time by thefirst device and the second device where at least a transceiver of thefirst device or the second device is in a power saving state.

In an eighteenth example and in furtherance of any of the previousexamples, a method may include the first frame comprising aclear-to-send (CTS) frame or a request-to-send (RTS) frame communicatedby one of the other devices.

In a nineteenth example and in furtherance of any of the previousexamples, a method may include the second frame comprising acontention-free end (CF-End) frame communicated by one of the otherdevices.

In a twentieth example and in furtherance of any of the previousexamples, a method may include determining a delta network allocationvector time equaling the difference between the transaction sessionstart time and the truncation time and adding the delta networkallocation vector time to a determined transaction session start timefor the subsequent transaction session to shift the subsequenttransaction session start time.

In a twenty-first example and in furtherance of any of the previousexamples, a method may include determining, by the processing circuitry,whether subsequent transaction sessions for the first device and thesecond device overlap subsequent transaction sessions for other devicesafter the subsequent transaction session start time has been shifted andshifting, by the processing circuitry, subsequent transaction sessionstart times until the transaction sessions for the first device and thesecond device do not overlap transaction session for other devices.

In a twenty-second example and in furtherance of any of the previousexamples, a method may include communicating, by the processingcircuitry, a transaction start time using a grant frame and acontention-free end (CF-End) frame, the grant frame comprising aduration field having duration information and a dynamic allocationinformation field having allocation duration information, the CF-Endframe comprising a duration field having duration information for theCF-End frame.

In a twenty-third example and in furtherance of any of the previousexamples, an article comprising a computer-readable storage mediumcontaining a plurality of instructions that when executed enable acomputing device to initiate a transaction session at a transactionsession start time to communicate a transaction between a first deviceand a second device, receive a first frame comprising informationindicating an occurrence of another transaction session between otherdevices and a time reservation to reserve time for the other transactionsession, receive a second frame comprising second information indicatinga truncation of the other transaction session at a truncation time andbefore an expiration of the time reservation and shift a subsequenttransaction session start time for at least one subsequent transactionsession between the first device and the second device based on adifference between the transaction session start time and the truncationtime.

In a twenty-fourth example and in furtherance of any of the previousexamples, an article comprising a computer-readable storage mediumcontaining a plurality of instructions that when executed enable acomputing device to the first frame received during a listening periodof the transaction session to determine if other devices arecommunicating on a channel to communicate the transaction during thetransaction session.

In a twenty-fifth example and in furtherance of any of the previousexamples, an article comprising a computer-readable storage mediumcontaining a plurality of instructions that when executed enable acomputing device to exit a standby mode of operation at the transactionsession start time by the first device and the second device where atleast a transceiver of the first device or the second device is in apower saving state.

In a twenty-sixth example and in furtherance of any of the previousexamples, an article comprising the first frame comprising aclear-to-send (CTS) frame or a request-to-send (RTS) frame communicatedby one of the other devices.

In a twenty-seventh example and in furtherance of any of the previousexamples, an article comprising the second frame comprising acontention-free end (CF-End) frame communicated by one of the otherdevices.

In a twenty-eighth example and in furtherance of any of the previousexamples, an article comprising a computer-readable storage mediumcontaining a plurality of instructions that when executed enable acomputing device to determine a delta network allocation vector timeequaling the difference between the transaction session start time andthe truncation time and add the delta network allocation vector time toa determined transaction session start time for at least one subsequenttransaction session to shift a transaction session start time for the atleast one subsequent transaction session.

In a twenty-ninth example and in furtherance of any of the previousexamples, an article comprising a computer-readable storage mediumcontaining a plurality of instructions that when executed enable acomputing device to determine whether subsequent transaction sessionsfor the first device and the second device overlap subsequenttransaction sessions for the other devices after the subsequenttransaction session start time has been shifted and shift subsequenttransaction session start times until the transaction sessions for thefirst device and the second device do not overlap transaction sessionfor the other devices.

In a thirtieth example and in furtherance of any of the previousexamples, an article comprising a computer-readable storage mediumcontaining a plurality of instructions that when executed enable acomputing device to communicate a transaction start time using a grantframe and a contention-free end (CF-End) frame, the grant framecomprising a duration field having duration information and a dynamicallocation information field having allocation duration information, theCF-End frame comprising a duration field having duration information forthe CF-End frame.

In a thirty-first example and in furtherance of any of the previousexamples, a method may include initiating a first transaction sessionwith a device at a transaction session start time, receiving informationcomprising an indication of a second transaction session with anotherdevice, and a time reservation for the second transaction session,receiving a truncation event of the second transaction session at atruncation time before expiration of the time reservation and shifting asubsequent transaction session start time for a subsequent transactionsession with the device based on a difference between the transactionsession start time and the truncation time.

In a thirty-second example and in furtherance of any of the previousexamples, a method may include exiting a standby mode of operation atthe transaction session start time where at least a transceiver is in apower saving state.

In a thirty-third example and in furtherance of any of the previousexamples, a method may include determining a delta network allocationvector time equaling the difference between the transaction sessionstart time and the truncation time and adding the delta networkallocation vector time to a preset transaction session start time toshift the subsequent transaction session start time.

In a thirty-fourth example and in furtherance of any of the previousexamples, a method may include determining whether subsequenttransaction sessions for the apparatus and the device overlap subsequenttransaction sessions for other devices after the subsequent transactionsession start time has been shifted and shift subsequent transactionsession start times until the transaction sessions for the apparatus andthe device do not overlap transaction sessions for the other devices.

In a thirty-fifth example and in furtherance of any of the previousexamples, a method may include communicating a transaction start timeusing a grant frame and a contention-free end (CF-End) frame, the grantframe comprising a duration field having duration information and adynamic allocation information field having allocation durationinformation, the CF-End frame comprising a duration field havingduration information for the CF-End frame.

In a thirty-sixth example and in furtherance of any of the previousexamples, an article comprising a computer-readable storage mediumcontaining a plurality of instructions that when executed enable acomputing device to initiate a first transaction session with a deviceat a transaction session start time, receive information comprising anindication of a second transaction session with another device, and atime reservation for the second transaction session, receive atruncation event of the second transaction session at a truncation timebefore expiration of the time reservation and shift a subsequenttransaction session start time for a subsequent transaction session withthe device based on a difference between the transaction session starttime and the truncation time.

In a thirty-seventh example and in furtherance of any of the previousexamples, an article comprising a computer-readable storage mediumcontaining a plurality of instructions that when executed enable acomputing device to exit a standby mode of operation at the transactionsession start time where at least a transceiver is in a power savingstate.

In a thirty-eighth example and in furtherance of any of the previousexamples, an article comprising a computer-readable storage mediumcontaining a plurality of instructions that when executed enable acomputing device to determine a delta network allocation vector timeequaling the difference between the transaction session start time andthe truncation time and add the delta network allocation vector time toa preset transaction session start time to shift the subsequenttransaction session start time.

In a thirty-ninth example and in furtherance of any of the previousexamples, an article comprising a computer-readable storage mediumcontaining a plurality of instructions that when executed enable acomputing device to determine whether subsequent transaction sessionsfor the apparatus and the device overlap subsequent transaction sessionsfor other devices after the subsequent transaction session start timehas been shifted and shift subsequent transaction session start timesuntil the transaction sessions for the apparatus and the device do notoverlap transaction sessions for the other devices.

In a fortieth example and in furtherance of any of the previousexamples, an article comprising a computer-readable storage mediumcontaining a plurality of instructions that when executed enable acomputing device to communicate a transaction start time using a grantframe and a contention-free end (CF-End) frame, the grant framecomprising a duration field having duration information and a dynamicallocation information field having allocation duration information, theCF-End frame comprising a duration field having duration information forthe CF-End frame.

Some embodiments may be described using the expression “one embodiment”or “an embodiment” along with their derivatives. These terms mean that aparticular feature, structure, or characteristic described in connectionwith the embodiment is included in at least one embodiment. Theappearances of the phrase “in one embodiment” in various places in thespecification are not necessarily all referring to the same embodiment.Further, some embodiments may be described using the expression“coupled” and “connected” along with their derivatives. These terms arenot necessarily intended as synonyms for each other. For example, someembodiments may be described using the terms “connected” and/or“coupled” to indicate that two or more elements are in direct physicalor electrical contact with each other. The term “coupled,” however, mayalso mean that two or more elements are not in direct contact with eachother, but yet still co-operate or interact with each other.

It is emphasized that the Abstract of the Disclosure is provided toallow a reader to quickly ascertain the nature of the technicaldisclosure. It is submitted with the understanding that it will not beused to interpret or limit the scope or meaning of the claims. Inaddition, in the foregoing Detailed Description, it can be seen thatvarious features are grouped together in a single embodiment for thepurpose of streamlining the disclosure. This method of disclosure is notto be interpreted as reflecting an intention that the claimedembodiments require more features than are expressly recited in eachclaim. Rather, as the following claims reflect, inventive subject matterlies in less than all features of a single disclosed embodiment. Thusthe following claims are hereby incorporated into the DetailedDescription, with each claim standing on its own as a separateembodiment. In the appended claims, the terms “including” and “in which”are used as the plain-English equivalents of the respective terms“comprising” and “wherein,” respectively. Moreover, the terms “first,”“second,” “third,” and so forth, are used merely as labels, and are notintended to impose numerical requirements on their objects.

What has been described above includes examples of the disclosedarchitecture. It is, of course, not possible to describe everyconceivable combination of components and/or methodologies, but one ofordinary skill in the art may recognize that many further combinationsand permutations are possible. Accordingly, the novel architecture isintended to embrace all such alterations, modifications and variationsthat fall within the spirit and scope of the appended claims.

What is claimed is:
 1. An apparatus, comprising: a memory; a transceivercoupled with at least one antenna; and a processor component to initiatea transaction session at a transaction session start time to communicatea transaction via the transceiver between the apparatus and a device,the transceiver to receive a first frame comprising informationindicating an occurrence of another transaction session between otherdevices and a time reservation to reserve time for the other transactionsession and to receive a second frame comprising second informationindicating a truncation of the other transaction session at a truncationtime and before an expiration of the time reservation, and the processorcomponent to shift a subsequent transaction session start time for atleast one subsequent transaction session between the apparatus and thedevice based on a difference between the transaction session start timeand the truncation time.
 2. The apparatus of claim 1, the transceiver toreceive the first frame during a listening period of the transactionsession to determine if other devices are communicating on a channel tocommunicate the transaction during the transaction session.
 3. Theapparatus of claim 1, the processor component to cause at least thetransceiver to exit a standby mode of operation at the transactionsession start time where at least the transceiver of the apparatus is ina power saving state.
 4. The apparatus of claim 1, the first framecomprising a clear-to-send (CTS) frame or a request-to-send (RTS) framecommunicated by one of the other devices.
 5. The apparatus of claim 1,the second frame comprising a contention-free end (CF-End) framecommunicated by one of the other devices.
 6. The apparatus of claim 1,the processor component to determine a delta network allocation vectortime equaling the difference between the transaction session start timeand the truncation time and add the delta network allocation vector timeto a determined transaction session start time for the subsequenttransaction session to shift the subsequent transaction session starttime.
 7. The apparatus of claim 1, the processor component to determinewhether subsequent transaction sessions for the apparatus and the deviceoverlap subsequent transaction sessions for other devices after thesubsequent transaction session start time has been shifted and to shiftsubsequent transaction session start times until the transactionsessions for the apparatus and the device do not overlap transactionsessions for other devices.
 8. The apparatus of claim 1, the processorcomponent to communicate, via the transceiver, a transaction start timeusing a grant frame and a contention-free end (CF-End) frame, the grantframe comprising a duration field having duration information and adynamic allocation information field having allocation durationinformation, the CF-End frame comprising a duration field havingduration information for the CF-End frame.
 9. The apparatus of claim 1,comprising: a housing comprising the memory, the processor component,the transceiver, and further comprising: a display; an input/output(I/O) device.
 10. A computer-implemented method, comprising: initiating,by processing circuitry, a transaction session at a transaction sessionstart time to communicate a transaction between a first device and asecond device; receiving, by the processing circuitry, a first framecomprising information indicating an occurrence of another transactionsession between other devices and a time reservation to reserve time forthe other transaction session; receiving, by the processing circuitry, asecond frame comprising second information indicating a truncation ofthe other transaction session at a truncation time and before anexpiration of the time reservation; and shifting, by the processingcircuitry, a subsequent transaction session start time for at least onesubsequent transaction session between the first device and the seconddevice based on a difference between the transaction session start timeand the truncation time.
 11. The computer-implemented method of claim10, the first frame received during a listening period of thetransaction session to determine if other devices are communicating on achannel to communicate the transaction during the transaction session.12. The computer-implemented method of claim 10, comprising: exiting, bythe processing circuitry, a standby mode of operation at the transactionsession start time by the first device and the second device where atleast a transceiver of the first device or the second device is in apower saving state.
 13. The computer-implemented method of claim 10, theshifting the subsequent transaction session start time comprising:determining a delta network allocation vector time equaling thedifference between the transaction session start time and the truncationtime; and adding the delta network allocation vector time to adetermined transaction session start time for the subsequent transactionsession to shift the subsequent transaction session start time.
 14. Thecomputer-implemented method of claim 10, comprising: determining, by theprocessing circuitry, whether subsequent transaction sessions for thefirst device and the second device overlap subsequent transactionsessions for other devices after the subsequent transaction sessionstart time has been shifted; and shifting, by the processing circuitry,subsequent transaction session start times until the transactionsessions for the first device and the second device do not overlaptransaction session for other devices.
 15. The computer-implementedmethod of claim 10, comprising: communicating, by the processingcircuitry, a transaction start time using a grant frame and acontention-free end (CF-End) frame, the grant frame comprising aduration field having duration information and a dynamic allocationinformation field having allocation duration information, the CF-Endframe comprising a duration field having duration information for theCF-End frame.
 16. A non-transitory computer-readable storage mediumcontaining a plurality of instructions that when executed enable acomputing device to: initiate a transaction session at a transactionsession start time to communicate a transaction between a first deviceand a second device; receive a first frame comprising informationindicating an occurrence of another transaction session between otherdevices and a time reservation to reserve time for the other transactionsession; receive a second frame comprising second information indicatinga truncation of the other transaction session at a truncation time andbefore an expiration of the time reservation; and shift a subsequenttransaction session start time for at least one subsequent transactionsession between the first device and the second device based on adifference between the transaction session start time and the truncationtime.
 17. The non-transitory computer-readable storage medium of claim16, comprising instructions that when executed enable the computingdevice to exit a standby mode of operation at the transaction sessionstart time by the first device and the second device where at least atransceiver of the first device or the second device is in a powersaving state.
 18. The non-transitory computer-readable storage medium ofclaim 16, comprising instructions that when executed enable thecomputing device to: determine a delta network allocation vector timeequaling the difference between the transaction session start time andthe truncation time; and add the delta network allocation vector time toa determined transaction session start time for at least one subsequenttransaction session to shift a transaction session start time for the atleast one subsequent transaction session.
 19. The article of claim 16,comprising instructions that when executed enable the computing deviceto: determine whether subsequent transaction sessions for the firstdevice and the second device overlap subsequent transaction sessions forthe other devices after the subsequent transaction session start timehas been shifted; and shift subsequent transaction session start timesuntil the transaction sessions for the first device and the seconddevice do not overlap transaction session for the other devices.
 20. Thearticle of claim 16, comprising instructions that when executed enablethe computing device to communicate a transaction start time using agrant frame and a contention-free end (CF-End) frame, the grant framecomprising a duration field having duration information and a dynamicallocation information field having allocation duration information, theCF-End frame comprising a duration field having duration information forthe CF-End frame.